Diindeno-Fused Dibenzo[a,h]anthracene and Dibenzo[c,l]chrysene: Syntheses, Structural Analyses, and Properties.

Diindeno-fused dibenzo[a,h]anthracene 6 and diindeno-fused dibenzo[c,l]chrysene 9 contain the key moieties 1,4-quinodipropene (1,4-QDP) and 2,6-naphthoquinodipropene (2,6-NQDP), respectively, and they both have an open-shell singlet ground state. The latter compound exhibits a strong biradical character and interesting properties, including a low ΔET-S (2.44 kcal mol-1 ), a small HOMO-LUMO gap (1.06 eV), a wide photoabsorption range (250-1172 nm), and a large two-photon absorption cross-section (σ=1342±56 GM). This work verifies that 6 has a slightly larger HOMO-LUMO gap and ΔET-S than its helical isomer diindeno[2,1-f:1',2'-j]picene (DIP), but is a much stronger two-photon absorber, verifying the important effect of geometry on the photophysical properties.

A Palladium- and Copper-Catalyzed Synthesis of Dihydro[1,2-b]indenoindole-9-ol and Benzofuro[3,2-b]indolines: Metal-Controlled Intramolecular C-C and C-O Bond-Forming Reactions.

A palladium- and copper-catalyzed synthesis of dihydro[1,2-b]indenoindole-9-ol and benzofuro[3,2-b]indolines has been developed, whereby the same starting material is employed for the synthesis of both heterocyclic scaffolds and the selectivity of the product is controlled by switching the choice of metal. Salient features of these cascade reactions include wide-ranging functional group tolerance, simple reaction conditions, and moderate to high yields.

Palladium(0)-catalyzed single and double isonitrile insertion: a facile synthesis of benzofurans, indoles, and isatins.

A palladium(0)-catalyzed cascade process consisting of isonitrile insertion and α-Csp(3)-H cross-coupling can be achieved for the synthesis of benzofurans and indoles. The construction of isatins by a Pd-catalyzed cascade reaction incorporating double isonitrile insertion, amination, and hydrolysis has also been achieved. The key features of this work include diverse heterocycle synthesis, phosphine-ligand-free reaction conditions, a one-pot procedure, simple and commercially available starting materials, broad functional-group compatibility, and moderate to good reaction yields.

An iron-catalyzed cascade approach to benzo[b]carbazole synthesis followed by 1,4-sulfonyl migration.

A simple and straightforward approach was developed to construct 5H-benzo[b]carbazole derivatives by iron catalysis in a cascade sequence. The notable features of this work include an atom-economical cascade sequence, unprecedented 1,4-sulfonyl migration, tolerance of a variety of functional groups, good yields, and an economical catalytic system.

Metal-free cycloaddition to synthesize naphtho[2,3-d][1,2,3]triazole-4,9-diones.

A metal-free domino [3 + 2] cycloaddition is reported to construct naphtho[2,3-d][1,2,3]triazole-4,9-dione derivatives and provide an alternative approach to the azide-alkyne cycloadditions. The key features are easily available starting materials, mild reaction conditions, a good atom economy, eco-friendly characteristics and a broad substrate scope with high yields.

Palladium(II)-catalysed regioselective synthesis of 3,4-disubstituted quinolines and 2,3,5-trisubstituted pyrroles from alkenes via anti-Markovnikov selectivity.

A novel strategy has been identified for the regioselective synthesis of 3,4-disubstituted quinolines and 2,3,5-trisubstituted pyrroles from simple alkenes via anti-Markovnikov selectivity under palladium catalysis. The salient features are synthesis of two different heterocycles, readily available starting materials, broad substrate scope, moderate to good yields and use of molecular oxygen as a terminal oxidant.

Au(I)-catalyzed synthesis of 8-oxabicyclo[3.2.1]oct-2-enes and 9-oxabicyclo[3.3.1]nona-2,6-dienes from enynol via oxonium/Prins-type cyclization.

A sustainable and simple Au(I) catalytic system to synthesise 8-oxabicyclo[3.2.1]oct-2-enes and 9-oxabicyclo[3.3.1]nona-2,6-dienes from enynol via oxonium/Prins-type cyclization is described. The key advantages of this reaction are selectivity, good functional group tolerance and a new approach for synthesis of oxabicyclic and oxatricyclic systems.

A one-pot hypoiodite catalysed oxidative cycloetherification approach to benzoxazoles.

A practical one-pot hypoiodite catalysed oxidative cyclization approach to synthesize α-ketobenzoxazole derivatives was successfully developed. This operationally simple protocol utilizes easily-accessible starting materials and has a broad substrate scope with excellent yields.